Maurice Ohuonu (l.) and Henry Gates work as one of three lead abatement teams that remove lead paint from homes in St. Louis., Feb. 26. The men scraped the windows of Anquanetta Williams' home in the 4300 block of Cote Brilliante Avenue, where Williams lives with two grandchildren, one with high lead levels.

Federal prosecutors in New York are conducting a wide-ranging investigation into health and safety conditions, particularly elevated blood lead levels, in the city’s public housing and homeless shelters.

The investigation, disclosed Wednesday in a letter from Preet Bharara, the US attorney for the Southern District of New York, and affirmed in a federal judge’s order, calls for the city’s health department to produce information about cases of lead paint exposure that led to elevated blood lead levels.

It also calls for information about “unsafe, unsanitary, or unhealthful,” conditions in public housing and shelters, The New York Times reports.

The probe comes amid renewed focus on lead poisoning following an ongoing crisis involving exposure to lead in tap water in Flint, Mich., as well as heightened scrutiny of conditions in New York's public housing accommodations. However, exposure to lead paint in federally subsidized housing isn't just a New York problem, advocates for stricter controls say.

At issue is the fact federal housing policy doesn’t require housing authorities to take action to move tenants, especially children, found to be exposed to lead until the amount of lead in their bloodstream reaches 20 micrograms per deciliter.

That’s far below the level at which the Centers for Disease Control recommends action be taken, which is 5 micrograms per deciliter for children aged 1 to 5.

In Chicago, that gap between the federal standards and the agency’s recommendations has affected at least 178 children living in publicly-funded housing since 2012, the Chicago Tribune reports.

“They treated me like I was nothing, like my daughter didn't matter," Lanice Walker, whose 4-year-old daughter was diagnosed with a blood lead level of 11 only months after she moved from public housing to a private rental in the city’s Austin neighborhood told the paper.

Much of her rent was paid for by a voucher for the city’s public housing authority, leaving her no other alternative options to move when she began to suspect that high lead levels in her home were affecting the health of her children.

The Chicago Housing Authority has promised to address the gap, but the authority had also allowed landlords to request indefinite extensions to fix lead paint hazards, the Tribune reports.

The CDC says at least four million households with children are being exposed to high levels of lead.

Congress has also attempted to close the gap, with Sen. Bob Menendez (D) of New Jersey and Sen. Richard Durbin (D) of Illinois introducing a bill earlier this month to require federal housing standards to be aligned with the CDC’s guidelines.

“No child should have to grow up in a home where simply breathing could hurt them,” Senator Menendez said in a statement. “We can’t sit idly by while millions of children in this country are suffering from the health effects of lead poisoning, and thousands more may be vulnerable to exposure.”

The bill would also require housing authorities to conduct new risk assessments for low-income housing built before 1978 prior to a family with a child under six moves in. In New Jersey, more than 3,000 children are diagnosed with lead poisoning from household paint and other sources each year, the state’s health department says.

In the New York investigation, court documents say the city’s Department of Health and Mental Hygiene had earlier refused to provide the information in response to a civil investigation without a judge’s order to avoid violating city and state health codes.

The health agency now says it is complying with the investigation, Nick Paolucci, a spokesman for the city’s law department told the Times.

Ritchie Torres, a Bronx Democrat who chairs the City Council’s Public Housing Committee called the agency “both poorly funded and poorly managed,” citing a survey he conducted finding of 200 residents in buildings managed by the housing authority, 63 percent said something was damaged or broken in their apartment.

“When you’re under investigation by Preet Bharara,” Mr. Torres told the Times, “that’s as serious as it gets.”